| Semiconductor piezoresistive sensor and operation method thereof -> Monitor Keywords |
|
|
 
Semiconductor piezoresistive sensor and operation method thereofRelated Patent Categories: Semiconductor Device Manufacturing: Process, Having Magnetic Or Ferroelectric ComponentSemiconductor piezoresistive sensor and operation method thereof description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070148788, Semiconductor piezoresistive sensor and operation method thereof. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This Non-Provisional application claims priority under U.S.C. .sctn. 119(a) on patent application Ser. No(S). 094145987, filed in Taiwan, Republic of China on Dec. 23, 2005, the entire contents of which are hereby incorporated by reference BACKGROUND OF THE INVENTION [0002] 1. Field of Invention [0003] The invention relates to a semiconductor sensor and in particular to a semiconductor piezoresistive sensor and an operation method thereof. [0004] 2. Related Art [0005] Pressure sensors have been widely used in various fields. According to different application fields and requirements, the principles of the pressure measurements include a piezoresistive type, a piezoelectric type and a capacitive type. Because the piezoresistive sensor has advantages such as high output voltage and high sensitivity, the measurement can be performed by utilizing the effect that the resistance of the material changes according to different stress. [0006] FIG. 1A is a schematic cross-sectional view showing a conventional semiconductor piezoresistive sensor 1. Referring to FIG. 1A, the semiconductor piezoresistive sensor 1 includes a semiconductor base 10, a piezoresistive element 11 and a circuit 12. The semiconductor base 10, such as a monocrystalline silicon base, includes a diaphragm 101 and a base 102. The base 102 fixes both ends of the diaphragm 101, and the piezoresistive element 11 is disposed within the diaphragm 101 for serving as the sensing device of the semiconductor piezoresistive sensor 1. The circuit 12 is electrically connected with the piezoresistive element 11 and the circuit 12 includes, for example, a complementary metal oxide semiconductor (CMOS), a bridge circuit, an amplifier circuit or a logic circuit for receiving and processing the signal output from the piezoresistive element 11. [0007] The semiconductor base 10 is an n-minus(n.sup.-)-type semiconductor, which is transferred into a p-minus(p.sup.-)-type piezoresistive element 11 by way of diffusion or ion implantation. Herein, a p-n junction is formed between the semiconductor base 10 and the piezoresistive element 11. As shown in FIG. 1A, both ends of the piezoresistive element 11 are electrically connected with a p-plus(p.sup.+)-type interconnect element 13, respectively. The circuit 12 is electrically connected to the p.sup.+-type interconnect element 13 through an opening 141 formed on an insulating layer 14, which covers the surface of the semiconductor base 10. [0008] When a voltage V is inputted to the semiconductor piezoresistive sensor 1, a negative space charge is formed below the p-type piezoresistive element 11, and the negative space charge drifts with time so as to cause the resistance of the piezoresistive element 11 to change with time such that the output signal of the piezoresistive element 11 drifts with time. In addition, the insulating layer 14 binds some positive surface charges due to the material characteristic of the insulating layer 14, which also causes the positive surface charges to drift with time, the phenomenon relating to the resistance of the piezoresistive element 11 that varies with time becomes more serious. Accordingly, the precision of the output signal of the piezoresistive element 11 is deteriorated. [0009] To solve the above-mentioned problem, another prior art discloses that an n-plus(n.sup.+)-doped region 15 is formed within the semiconductor base 10, as shown in FIG. 1B. Then, a proper voltage is inputted to the n.sup.+-doped region 15 to form a reverse bias at the p-n junction so as to limit the current in the piezoresistive element 11. Thus, the phenomenon of the reduced precision of measurement of the semiconductor piezoresistive sensor 1 due to the leakage current can be improved. However, in the process of manufacturing the conventional p.sup.--type piezoresistive element 11, additional manufacturing processes, such as doping and thermal diffusion, and costs for masks which are necessary during the process of forming a n.sup.+-doped region 15 within the n.sup.--type semiconductor base 10. [0010] Therefore, it is an important subject of the invention to simplify the manufacturing process and effectively improve the phenomenon that the resistance of the piezoresistive element varies with time. SUMMARY OF THE INVENTION [0011] In view of the foregoing, the invention is to provide a semiconductor piezoresistive sensor, which is manufactured with simple processes so as to reduce the manufacturing cost and effectively enhance the precision of measurement, and an operation method thereof. [0012] To achieve the above, a semiconductor piezoresistive sensor of the invention is electrically connected with a circuit. The semiconductor piezoresistive sensor includes a semiconductor base, at least one piezoresistive element and a conductive layer. The semiconductor base includes a diaphragm and a base disposed adjacent to and around the diaphragm. The piezoresistive element is formed in the diaphragm and is electrically connected with the circuit. The conductive layer is electrically connected with the diaphragm. Further, the semiconductor piezoresistive sensor includes an insulating layer and a shield layer, the insulating layer is disposed on the semiconductor base and covers the piezoresistive element, the shield layer is disposed on the insulating layer and covers at least a part of the insulating layer [0013] To achieve the above, the invention discloses an operation method of a semiconductor piezoresistive sensor. The operation method includes the steps of applying a first voltage to the circuit and applying a second voltage to the conductive layer. When a value obtained by subtracting the second voltage from the first voltage is less than a turn-on voltage between the piezoresistive element and the diaphragm, a junction between the piezoresistive element and the diaphragm forms a reverse bias or the junction is turned off. [0014] To achieve the above, the invention also discloses a semiconductor piezoresistive sensor which is electrically connected with a circuit and includes a semiconductor base, at least one p-doped piezoresistive element, and a conductive layer. The semiconductor base has an n-doped base, and the at least one p-doped piezoresistive element is formed in the n-doped base. The conductive layer is electrically connected with the n-doped base so as to form a regional high doping concentration area, whereby surrounding the at least one p-doped piezoresistive element. [0015] As mentioned above, the conductive layer or the shield layer is electrically connected with the diaphragm of the semiconductor base in the semiconductor piezoresistive sensor and the operation method thereof according to the invention. The conductive layer and the shield layer respectively include the conductive material and the non-insulating material. When the semiconductor piezoresistive sensor of the invention is applied to a circuit and a proper voltage is inputted into the conductive layer or shield layer, the junction between the piezoresistive element and the diaphragm is formed with a reverse bias or the junction is turned off such that the current is limited within the piezoresistive element. Therefore, the phenomenon of the drift of the output signal of the piezoresistive element is improved. Compared to the prior art, it is unnecessary to form a semiconductor doping region, which is different from the piezoresistive element, on the semiconductor base in this invention. Thus, the manufacturing process is effectively simplified, the manufacturing cost is reduced, and the precision of measurement of the semiconductor piezoresistive sensor is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS [0016] The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein: [0017] FIGS. 1A and 1B are schematic cross-sectional views showing the conventional semiconductor piezoresistive sensor; [0018] FIGS. 2A and 2B are schematic cross-sectional views showing a semiconductor piezoresistive sensor according to a first embodiment of the invention; [0019] FIGS. 3A and 3B are schematic cross-sectional views showing a semiconductor piezoresistive sensor according to a second embodiment of the invention; [0020] FIGS. 4A and 4B are schematic cross-sectional views showing a semiconductor piezoresistive sensor according to a third embodiment of the invention. [0021] FIG. 5A is a schematic view showing a semiconductor piezoresistive sensor according to a fourth embodiment of the invention; and Continue reading about Semiconductor piezoresistive sensor and operation method thereof... Full patent description for Semiconductor piezoresistive sensor and operation method thereof Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Semiconductor piezoresistive sensor and operation method thereof patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Semiconductor piezoresistive sensor and operation method thereof or other areas of interest. ### Previous Patent Application: Methods of forming magnetic random access memory devices having titanium-rich lower electrodes with oxide layer and oriented tunneling barrier Next Patent Application: Insulator film characteristic measuring method and insulator film characteristic measuring apparatus Industry Class: Semiconductor device manufacturing: process ### FreshPatents.com Support Thank you for viewing the Semiconductor piezoresistive sensor and operation method thereof patent info. IP-related news and info Results in 0.30785 seconds Other interesting Feshpatents.com categories: Software: Finance , AI , Databases , Development , Document , Navigation , Error 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
